1. Field of the Invention
The invention is a metal bond which processes at higher temperatures while maintaining the mechanical properties such as hardness of the fillers used in the bond. The invention is further the abrasive tools made from the metal bond.
2. Technology Review
Metal bonded diamond abrasive grinding wheels are used in the edge grinding of glass. These wheels typically contain a metal bonded diamond abrasive applied to a metal core. To produce a wheel, the metal bonded diamond abrasive is bonded by a hot-pressing or hot-coining process to the metal core.
The metal bond which contains the diamond abrasive generally comprises a combination of several metals and a steel filler. The compositions of the metal bonds should be selected to optimize both the efficiency of cut and the wheel life. To increase the wheel life, the bond preferably contains fillers with high hardness and a bond with little or no porosity after processing. To improve the efficiency of cut which is a measure of the rate at which a given length of glass edge can be ground, the bond preferably contains certain hard phases such as a copper-titanium phase which allow the bond to be durable and yet fracture periodically thereby improving the bonds ability to release dull or worn abrasives which increases the grinding rate or the efficiency of cut.
The steel fillers typically used in grinding wheels are alloy steels. These fillers result in wheels which do not have both an optimized efficiency of cut and wheel life. This is because these alloy steels have a hardness of from 300-700 kg/mm.sup.2 before processing which decreases when the metal bonded diamond abrasive to which the fillers are added are hot-pressed at the higher temperatures required to eliminate porosity from the finished product. When the metal bonded diamond abrasive is hot-pressed at the lower temperatures required to maintain the hardness of the steel filler, porosity in the finished product is not removed. This porosity can only be removed at lower temperatures by using higher hot-pressing pressures which results in decreased life of the graphite hot-pressing molds and results in higher processing costs.
Another drawback of processing the metal bonded diamond abrasive at lower temperatures is the absence of certain brittle phases in the bond such as the copper-titanium phase allow the bond to fracture periodically and thereby improve the bonds ability to release dull or worn abrasives. This phase tends to form at higher temperatures and does not appear or appears in lower concentrations at these temperatures thereby decreasing the efficiency of cut.
It is therefore an object of this invention to create a metal bond that can be incorporated in a wheel and result in both increased wheel life and efficiency of cut.